Bonding panels to base surfaces



May 9, i961 H. l. scHER ET AL 2,983,305

BONDING PANELS To BASE sURFAcEs Filed Jan. 12, 1959 50 a "56 INVENTORS@Z9 5 gwM/@Mw Q@ ATTORNEY ce t :iafenta 'May ggf-19er i sometimes beenemployed to supply the required bond,

vaysou ov` tiorrto effect evacuation.; y

- Anobpct ofmthehpresent inyention is topro de,ne\l

improved` methods ofapplying high pressures uniformly i to panels beingbonded to base surfaces. 2,983,305 Still another object of the inventionis to provide sinr'-,y pliied and inexpensive methods for creatingauvacuunr BONDING PANELS T0 BASE SURFACES Y 5 beneath large panels beingbonded to wall surfaces, and Herbert I. Seher and John S. Dunn,Baltimore, Md., asthe like, to utilize the exterior normal atmosphericpres- Sigllols t National Plastic Products C0 Odelfn, Mil-y sure 'astherequired uniformly `applied high pressure for a corpi-ration 0fMaryland curing resinous thermosetting adhesive bonding agen'fsl is N786 433 k Other objects and the nature and advantages off the FiledJan..12 1959 er o invention will be apparent from the following detailed10 Claims. (CL 154-41)v description, when considered Ain conjunctionwith the ac# companying drawing, wherein; ,y

Figi l is a plan elevation `View ofv a planular decoraff tive laminatebeing bonded to a base surface in accord-l ance with amethod embodyingthe invention; FigL 2 is a vertical section'taken along theline 2442 ofFig. l;y d Fig. 3 is an enlarged vertical section of a portionof thellaminate [shown in Figs. l Yand 2 at la subsequent 'stage of themethodg` i' This invention relates to methods' `of bonding panels to l5base surfaces', and 'more particularly -to methods of bonding planillardecorative laminates to wall surfaces and the like. d

Plaiiular decorative laminates, or other types of panels, are'oiftenilsed to provide decorative and protective sur- 20 faces on walls, doorsand table tops, as well as bar and counter tops, and the likelInthebonding'of `such panels to the base surfaces numerous problems havebeenenf countered. For example, when nails or screws are used for thispurpose, it is necessary to employ an elaborate nishing'treatment tohide the nail or screw heads in the f joints between adjacent panels.Contact cements have a portion of a laminate being bonded to a yhaseadjacent to a previously mounted laminate, and f l"Fig'x'S- is atransverse vertical section, vgenerally corre: spending to Fig. 2, of aplanularl'decorative laminate shown being bonded to a base surface inaccordance with a method constituting a second embodiment of theinvention. f yOne well known type of decorative laminate is con-Lstructed from a core' composed of several superposed sheets of kraftpaper impregnated with a phenol-formale, dehyde thermosetting resin,superimposed on said core is a print or pattern sheet composed of alphaeellulo'sepaper impregnated with a melamine-formaldehyde resin,and-covering the print sheet is a translucent or` trans-fvparentprotective overlay sheet composed ofl `alpha cel-v llose `orrayon impregnated with a melamine-formaldehyde resin, all of' saidsheetsbeing consolidatedby application theretoof highmpressures'D andelevatedtempera `ttes lt'oproduceaiinished planular laminate.Decorative' aminates'of this type orten .eiihibit apronounced but thebonding powerand the durability `of such cements have often beeninadequate. The application of mechan'ically applied pressure. to holdthe panels 'in posi- Ation lduring the curing of thermosetting.adhesivesvor 'glues' has usually been accomplished ybyhmeansfof acomplicated jiggingofclainps, braces, wedges 'and struts.

complicated procedure was not only expensive and laborious, kit'oftencaused ripples or other siii-face i. defeats reappear' on 'the panas,due to the localized 'ape plication ofthe pressure.` 't ges olifered bymodern highstren'gtli low cost, resinosthermo-setting adhesiveshaye beenwell 40 kz 4wn, but these adhesives generallyfrequire 'th "appli` @ad me1115.9! Y, fmefhds, P been L itestl'ydifficult,` ifnot impossible,t'ofapply high pressureswnifoirnly over the entirey areajolthey panelsduring the curingof the adhesive applied the o.' lnjceitainmanufacturing operations involvingthe usent these ac lliedsii-1es lasYbonding agents, it has beencustomary toiiisertth iclesbeing bonded intoaileible A Y ch; as alrublierbag, which is thenevacuatdfor th purpose ofutilizing resultant.pressure differential l progressively Amorepronounced during any subsequent ged 'istorage. YSuch Vwarpage ismanifested by transverse' curling 'wherein the laminates become arcuatein cross-section, and'usually the decorative melamine resin'impregnatedtopsurface of the laminates becomes concave t contour. However, in someinstances the top ls o substantial warpage may occur, In any.

adequately/high and u. iform or e lbondingof a'rl cles and in-rpr'oved`methods for bondingy panels `tofb, as efsur Fig. 4 is a verticalsection', corresponding .to lig.

surface. may instead becomei convexly warped, and. in

5 5 A. In, onder to s'implify, the work of mounting panels,

ma beem yed'tocover'an entire .tabla-atop,orto*cover contact-typ'yefc'ein entsf employed in lthe Amethods known Y'tjrequiredltheapplication ofvsuch high'l 'lgiparpgqvrmethods fo;ubonding planing; decorative-1. o pressures f0tp11nngthereof-,...The-utilization pf methode laminates-t0 ,wall,surfaces,:andthelikeff1; embpqyingthe'pressnt inventicnrrorfholdingsuclrpaielsf` y in placeand for uniformly applying :high pressuresthere, Jg. I

permits 4the-use of high strength, low cost, resinous thermosettingadhesives as the bonding agent.

In accordance with the present invention, panels are bounded to basesurfaces by resinous thermosetting adhesives requiring theapplication ofhigh pressures for proper curing thereof, and such pressures are createdby evacuation of the atmosphere from around and beneath the panelbeingmounted, whereby normal atmospheric pressure forces the panelagainst the base surface to which it is being bonded. The panel istemporarily framed or covered by disposable plastic strips or sheetskwhich are sealed air tight therearound, and are provided on theperiphery thereof with a connecting member adapted to providecommunication with a source of vacuum. After the vacuum created pressurehas been applied for a predetermined period of time suiicient for thethermosetting lresin tohave substantially completely cured, the plasticstrips or sheets may be removed and discarded or reused.

VIt is evident that the base surface to which a panel is secured bymethods embodying the invention must be relatively rigid andnon-porouslor air-impervious. Wall sur- Vfaces should be previously tested todetermine their porosity. If necessary the `base surfaces may besuitably treated to prevent air leakage. Thus, if the base or mountingsurface is constructed from plywood or hard- Woodlumber sections, thebutt joints between sections should be sealed with wood putty orcaulking compound, and any protruding nail heads should be driven flushwith thev mounting surface.

Referring to Figs. 1 and 2, a rectangular decorativelaminate panel isshown being afxed to la flat base surface 12, such as a table top or awall of a room. By way of example, in this instance the panel `1t) is'generally planular, but it is slightly concavely warped, so that itscenter portion rests in cont-act with the base 12 and the outer edges ofthe panel 10 jut upward-ly therefrom. An airtightjseal between the kbasesurface 12 and the edges of the panel 10 is formed by placing along eachedge of the panel 10 a plastic strip 14, which 'overlaps a portion olfthe base 12 and the adjacent edge of the panel 10. The plastic strips 14should be made from a relatively strong, semi-rigid material, such astive to ten mil thickness unplasticized polyvinyl chloride sheeting, sothat the strips will not burst or collapse when a vacuum is created onone side thereof. Although the strips 14 may themselves be madeadhesive, or they may have an adhesive coating applied on one sidethereof, -it is preferable to secure the strips v14 in theabove-described overlapping position and form an airtight seal therewithby overlapping the opposite edges of the strips 14 with sections 16 ofthin, flatback, pressure sensitive paper adhesive tape.

The four side edges of the rectangular panel 10 may be covered inoverlapping relation by four of the strips 14 applied separately insuccession, or the four strips 14 may be previously united at theirendsto form in effect a unitary peripheral frame for the panel 10. Itisevident that it iis more',v convenient to utilize separate strips, sincethey maybereadily cut from a Vlarge roll to the desired length, therebyeasily fitting panels of different sizes. p

*One off the'four strips 14, or one side of any unitary peripheral framesubstituted therefor, is provided withfan outwardly projecting extension18 having an aperture 2li` formed'therein for connection with a suitableoutside source ofsuction?. In Fig. 2 a suction cup22 is showny beingplaced in operative position covering the aperture 20,' and suitableadhesive tape may be used to seal it in said position. Due to the'`concave Warpage of the panel 10, tapered spaces'24 are Vformed beneaththe upwardly jutt'ing vedges thereof prior tothe application olf thesuction. After the suction is applied theedges of the panel 10 areforced'downwardly by the normal exterior atmospheric lso Y 4 viding aperipheral channel leading to the aperture 20 for sucking theIatmosphere from around all four sidesand from beneath the panel 10.

Usually it is advisable to test the base surface for porosity and airleakage before applying the thermosetting adhesive employed as thebonding agent between said surface and the back of the panel. This maybe aecomplished by placing the panel 10 in its desired ultimate positionin the manner described in `detail hereinabove, applying a vacuum of atleast about ten inches of mercury,'and determining how well the vacuumholds while the vacuum pump continues to operate. If it is determinedthat the vacuum holds satisfactorily, the panel 10 and its assembly ofplastic strips 14 and adhesive tapes 16is carefully red moved from thebase surface 12 without tearing or otherwise disturbing the strips andtapes. The base surface 12 is next covered with a layer of a suitableresinous thermosetting adhesive. In placing the layer of adhesivebetween the panel and the base surface, itis evident that the adhesivemay be applied either to the panel `or to' the base surface. Then thepanel 10 is returned to its former position on the base surface. Theplastic strips 1 4 and the adhesive tapes 16 are carefully pressed intoposition again to form an airtight seal, and the suction cup 22 isplaced over the aperture 2t) to create a vacuum around and beneath thepanel 10. This vacuum is maintained for from about thirty minutes toabout three hours, depending upon the speed of curing of the particularadhesive used. At the end of this time, the strips 14 and the tapes 16maybe removed, and it will be found that the panel 10 is securely anduniformly bonded to the base surface. l The resinous adhesive employedmay be any of many well known varieties requiring high pressures toeffect curing thereof. A commercially available modified ureaaldehydeadhesive has been found to give good results. Certain acidic catalystsmay be incorporated into the adhesive to accelerate its curing rate, butcare must be taken to establish a proper balance between bond stabilityand curing speed, since excess acid may cause degredation of wallsurfaces made of wood or other cellulose products. I The size of thepanel being applied is limited slightly by the fact that marginal spaceshould be provided for temporarily mounting the plasticstripsand thevadhesive tapes used in the bonding operation. Thus, a panel beingmounted on a wall of a room should not extend completely from theceiling to the floor thereof. However, ceiling furring may besubsequently installed to cover the top edge of such a panel, andl abaseboard would normally cover the bottom edge thereof. p Y

Fig. 4 simply shows the manner in which one panel may be mounteddirectly adjacent to a previously erected panel. Inthis view a pair ofdecorative laminate panels 40 are mounted edgewise close to eachother'ona hat base surface 42. Either one of the panels 40 may be considered ashaving been previously bonded tothe base 12, and the other one of thesepanels is shownrin the process of being mounted. A plasticstrip 44,corref sponding to one of the previously described vstrips 14,

pressure until said edges rest flatly in contact with the base surface12, as shown in Fig. 3 It should be observed that the-plastic strips v14yrernain'uncollapsed despite the relatively sti'ong vacuum'V existingtherebeneath, thereby prooverlaps the adjacent edges vof the two panels40, and suitable lengths of adhesive tape 46 overlap the edges ofthe-strip 44, thereby forming an airtight seal therewith. A vacuum isthen applied for the duration vof the curing cycle of the resinousadhesive bonding' agent, in theA same manner as has been described inregard to theembodi-A ment ofthe invention illustrated in Figs. 1 and 2.

InFig. 5 a kdecorative laminate` panel 50, which'is slightly conveXlywarped, is shown in `the process of being prepared `for attachment to aflat base surface 525 "Bei cause of the convex warpage of the panel 50,'its-side edgeslcontact the base surface 52, but its center'plirtonlprotrudes upwardly above said surface. Y It is possible to bond thepanel 50 to the base 52 by using a plurality of plastic strips andlengths of adhesive tapeinexactly the same manner described for thepanel 10 shown in S Figs. l and 2. However, in view of the fact that theside edges of the convexly warped panel 50 tend to creep outwardly whenthe panel becomes flattened by the application of suction therebeneath,this creeping action may cause disruption of such strips and consequentbreaking of the airtight seal. Therefore, it is preferred to cover theentire -upper side of the panel 50 and also to overlap its four sideedges by means of a unitary plastic sheet 54, which may otherwisecorrespond in composition and in thickness to that of the previouslydescribed plastic strips-14. One side edge of the sheet 54 is providedwith an outwardly projecting extension 56 having an aperture 58 formedtherein for communication with a suction cup 60. A plurality of sections62 of pressure sensitive adhesive tape overlap the edges of the sheet 54and its eX- tension 56 to form an airtight seal with the base surface52. The step of rst testing the base surface for air leakage, and theother steps of the bonding procedure, are performed in the same manneras has been previously described.

rIlhe use of a unitary plastic sheet for entirely covering a panel andalso overlapping its four side edges, as shown in Fig. 5, may also beemployed advantageously when it is desired to bond panels to curved basesurfaces. Similarly, specially contoured panels, such as post-formeddecorative laminates, may be successfully bonded by this method tocurved base surfaces, without employing the to what is shown in thedrawings and described lin the specification, but only as indicated inthe appended claims.

What is claimed is.

l. A method of bonding panels to base surfaces, comprising the steps ofapplying a layer of a resinous thermosetting adhesive between a paneland `a base surface, placing the panel upon said surface in position tobe bonded thereto by the adhesive, placing a sealing strip along theperipheral edges of the panel to form an airtight seal between saidedges and said surface, providing a connection with a source of suctionthrough said strip at one edge of the panel, applying a vacuum from saidsource to evacuate the air from around the edges and beneath the panel,whereby the panel is `forced against said surface by normal exterior-atmospheric pressure, maintaining the vacuum until the thus appliedpressure has caused the adhesive to lbecome cured, and then removingthesealing strip. l

2. A method of bonding panels toy basesurfaces, com- 6 of said frame isprovided with an aperture for forming a connection with the source ofsuction.

5. A method of bonding panels to base surfaces, comprising the steps ofapplying a layer of a resinous thermosetting adhesive between a paneland a base surface, placing the panel -upon said surface in position tol'be bonded thereto by the adhesive, covering the panel including itsperipheral edges with a sealing sheet in overlapping relation with thebase surface to form an airtight seal therewith, providing a connectionwith a source of suction through said sheet at one edge of the panel,applying a vacuum from said source to evacuate the air from around theedges and beneath the panel, whereby the panel is forced against saidsurface by normal exterior atmospheric pressure, maintaining the- Vacuumuntil the adhesive has cured, md then removing the sealing sheet.

6. A method of bonding panels to base surfaces, comprising the steps ofapplying a layer of a resinous thermosetting adhesive between a paneland a base surface, placing thevpanel upon said surface in position t0be bonded thereto by the adhesive, placing a plastic strip along each ofthe peripheral edges of the panel in overlapping relation with the basesurface, sealing said strips to the panel and the base surface to forman seal therebetween, providing a connection with a source of suctionthrough one of saidA strips at one edge of the panel, applying a vacuumfrom said source to evacuate the air from around the edges and beneaththe panel, whereby the panel is forced against said surface by normalexterior atmospheric pressure, maintaining the vacuum -until theadhesive has cured, and then removing the strips.

7. The method defined by claim 6 wherein the plastic strips are sealedto the panel and to the base surface lby applying a pressure sensitiveadhesive tape along the edges of the strips in overlapping relationthereto.

8. The method defined by claim 6 wherein the plastic strips placed alongeach of the peripheral edges of the panel are applied separately insuccession, and one of Asaid strips is provided with an aperture forforming a connection with the source of suction.

9. A method of Ibonding panels to base surfaces, comprising the steps ofapplying a layer ,of a resinous thermosetting adhesive between a paneland a base surface, placing the panel upon said surface in position to ibe bonded thereto by the adhesive, covering the entire prising the stepsof applying a layer ofa resinous thermosetting adhesive betweenk a paneland a base surface,

placing the panel upon said surface in position tofbe bonded thereto bythe adhesive, covering the ,peripheral edges of the panel with a sealingstrip in overlapping relation with the lbase surface to forman airtightsealV therewith, providing a connection with a source of suction throughsaid strip at one edge of the panel, applying a vacuum from said sourceto evacuate the ,air from aroundthe edges and beneath the panel,wherebythe panel is forced against said surface by normal' exterioratmospheric pressure, maintaining the lVacuum until the vaclhesivehascured, andv thenremovingfthe sealing strip.

' 3. The method defined by claim 2, "wherein the peripheral edges of thepanel are covered by a plurality of one of said' individual strips isprovided-:with Yan aperindividual strips applied' separately insuccession, and *A i ture for forming a connection with'r the sourceofsuction, 'Y

4. The method defined by claim 2, wherein the'pe-y ripheral edges vofthe panel arevc'overed by"a peripheral frame constructed from a"pluralitycfstripsunited fat their-'ends Aand applied as a Asingle unit,Vand one side top of the panel including its peripheral edges with aplastic sheet in overlapping relation with the -base surface, sealingthel edges of said'sheet to the base surface to form an airtight seal,providing a connection with va source of suction through said sheet atone edge ofthe panel, aplying a vacuum from said source to evacuate theair from around the edges and beneath the panel, whereby the panelV isforced against said surface by normal exterior atmospheric pressure,maintaining the r l'elerenc-esv Cited ini'thefiile of this patentYUNITED YSTATES rATnI- ITSI

